The present invention relates to a composite member comprised of a diecast part and a hub part which is of a harder material than the diecast part and to which the diecast part is diecast within a diecast mold.
Such a composite member is known for example from U.S. Pat. No. 5,094,076. This composite member comprises a hub part surrounded by a plastic part attached to the hub part by an injection molding process. The plastic part is injection-molded during manufacture of the composite member whereby a transmission cone comprises abutments for sealing plates which are to prevent that the injection molding material reaches the inner areas of the hub part. It is disadvantageous that separate sealing plates are required which must withstand the injection molding pressure.
When, on the other hand, a diecast part, for example, is to be manufactured of aluminum, a diecasting pressure of 400 to 600 bar is required which makes necessary a correspondingly strong embodiment of the sealing plates.
It is furthermore disadvantageous in regard to the aforementioned solution that with the closed embodiment of the composite member the roller overrunning clutch is completely sealed within the hub part so that lubrication at a later point in time cannot be performed without destroying the composite member, and it is thus impossible to connect the roller overrunning clutch to the lubricant circuit of a hydrokinetic torque convertor. Furthermore, the additional arrangement of sealing plates requires a precise adjustment, to be achieved with a special cone structure, in order to avoid unbalance.
The roller overrunning clutch requires furthermore that the areas of the hub part facing the rollers are as hard as possible since with the special construction of a roller overrunning clutch considerable radial forces must be transmitted so that a hardened embodiment is necessary especially in order to prevent premature wear.
It is possible to manufacture the sealing plate according to U.S. Pat. No. 5,094,076 of a comparatively soft material that is thus suitable for sealing purposes. However, the sealing effect is over all dissatisfactory since by providing the additional component there is practically also an additional sealing location present, and the function of the sealing plate thus depends greatly on the exact machining of the hub part, respectively, the uniform pressing force via the abutments of the cone structure provided thereat.
It is therefore an object of the present invention to provide a composite member of the aforementioned kind that, despite wear resistance of the hub part, allows for a safe sealing during injection casting or diecasting of the diecast part.